There is a need for a measuring apparatus that will indicate a variety of output parameters of a user of any power-using device having a pedal-crank assembly, whether stationary or movable. Prior attempts to measure various output parameters of the user have been made primarily on stationary pedal-crank assemblies in the form of stationary exercise bicycles or ergometers. Stationary bicycles require a means to apply an artificial work load, such as a friction brake, an electric generator, or a constant-speed electric motor to simulate a range of load conditions. These work load devices control the torque and power the user must produce. The torque and power required for a user riding a bicycle along a road, however, are determined by the user by the choices of the gearing and speed, but also are affected by many factors such as: the mechanical condition of the bicycle, the condition of the road surface, the slope of the road, the total weight of the user plus bicycle and load, the wind speed and direction, and the acceleration. No matter what combinations of the above factors apply, parameters such as torque, power and work can now be displayed instantaneously to the user of any pedal-crank assembly.
M.J.A.J.M. Hoes et al. in a publication in Int. Z. angew, Physiol. einschl. Arbeitsphysiol. entitled "Measurement of Forces Exerted on Pedal and Crank During Work" discusses the results of force measurements on the pedal and crank at different angular positions.
Bargenda, U.S. Pat. No. 4,141,248, discloses an ergometer with a generator which can be controlled to provide a constant, preset power load. The product of a tachometer signal, which is proportional to the rotational speed, and the average torque, which is determined from an integrator circuit connected to a series circuit of two strain gauges with one mounted on each crank arm, provides a signal that when compared to another preset signal determines the control voltage going to the generator.
Chiles, U.S. Pat. No. 4,244,021, discloses an exerciser using a work generator coupled to the pedal assembly and wherein a programmed microprocessor is used to provide a constant power selected by the user and to provide data concerning the work done and heart rate.
Hull et al, U.S. Pat. No. 463,433, discloses a means for indicating the pedaling efficiency of a user by using strain gauges mounted on a single bicycle pedal in order to determine the ratio of force exerted perpendicular to the crank arm and force exerted parallel to the crank arm. On the road use and biofeedback are emphasized.
Brandstetter, U.S. Pat. No. 4,141,245, discloses a device for determining work and power by measuring the force of a flexible chain drive and multiplying that value by a measured value of the distance or of the speed. Use on a bicycle or motorcycle is discussed.
Chapter 5 of Science of Cycling, edited by Edmund R. Burke, discusses a variety of studies of biomechanical parameters which have been done on stationary ergometers.